Kahon

A binary encoding for JSON, optimized for write-once / read-many workloads with selective path retrieval.

See spec.md for the format specification.

Implementations

• jankdc/kahon-rs — Rust writer/encoder

Conformance Vectors

Lives in ./conformance/*.json. Each vector pairs a JSON input or constructed file with the exact bytes a conforming implementation must produce or reject.

Manifest schema

Each manifest is a JSON array of vectors. Common fields:

{
  "id": "category/short-name",
  "description": "One-line summary",
  "spec_refs": ["§4", "§5.2"],
  "bytes_hex": "4B41484E 0100 ... 4B41484E"
}

Fields by manifest:

• valid.json: adds json_text (the JSON literal as a string - preserves textual distinctions like 1 vs 1.0).
• invalid.json: adds must_reject: true and reject_reason (cites the invariant or rule violated).
• tolerated.json: adds writer_compliant: false, reader_should_accept: true, and (when applicable) json_text plus a minimal_form_id cross-reference to the conforming encoding in valid.json. Forward-compatibility entries (e.g., Extension codes) have no JSON correspondence and may set json_text and minimal_form_id to null.
• writer-rejects.json: omits bytes_hex. Adds json_text, writer_must_reject: true, and reject_reason (the §5/§11.2 rule violated).

bytes_hex is whitespace-tolerant; spaces are decorative. Strip non-hex characters before parsing.